Twelve aborted foetuses (gestational ranged from 4–9 months) and dams from dairies cattle farms in (Mashhad) Iran were analysed to investigate the participation of Neospora caninum in abortion. Diagnosis of the infection was determined by histopathology, serology (indirect fluorescent antibody test [IFAT]) and semi-nested polymerase chain reaction (PCR). A total 33% of bovine foetuses were considered to be infected by PCR technique. Microscopic lesions consistent with N. caninum infection in foetal brains were observed in 25% of the samples, whereas 33% were positive using IFAT (with a cut-off titre of 1:20). This study confirms the importance of N. caninum as an important cause of abortion in Iran.